In pursuit of higher engine efficiencies, higher turbine inlet temperatures have been relied upon to boost overall engine performance. This can result in gas path temperatures that may exceed melting points of turbine component constituent materials. To address this issue, dedicated cooling air is extracted from a compressor section and is used to cool the gas path components in the turbine, such as rotating blades and stator vanes for example, incurring significant cycle penalties.
One method of cooling turbine airfoils utilizes internal cooling passages and/or a baffle. Typically, film cooling holes and significant volumes of cooling air are required to provide the needed amount of cooling. To augment the internal cooling, the internal cooling passages have been configured to include treatments such as pedestals, air jet impingement, and turbulator treatment for passage walls. Pedestals are typically used to augment the two dimensional flow field for cooling passages that have very thin sections, such as double-wall cavities for example.
Another method provides an augmentation of the surface area available for cool-side heat transfer. One example of this method is the use of pins for a backside of a combustor panel. One disadvantage of using pins and pedestals is that these structures need to be kept with a normal direction toward a pull-plane of the casting dies. In a configuration with pedestals in a stamped metallic core, this means that the pedestals will always be normal to the cavity flow direction commensurate with the action pressing the core.